Cationic Side-Chain Attachment to Poly(Phenylene Oxide) Backbones for Chemically Stable and Conductive Anion Exchange Membranes

Jing Pan, Juanjuan Han, Liang Zhu, Michael Anthony Hickner

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

A series of chemically stable and ionically conductive side-chain anion exchange membranes (AEMs) based on poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) backbones and alkyltrimethylammonium cations are reported in this work. Two alkyltrimethylammonium groups with n-propyl (C3) and n-pentyl (C5) alkyl chains were tethered onto PPO backbones through secondary amine moieties, resulting in two side-chain AEMs, that is, NC3Q-PPO and NC5Q-PPO and NC5 Q-PPO. In comparison to benzylic QA groups (e.g., benzyltrimethylammonium cations in quarternized PPO (QPPO) and benzylalkyldimethylammonium cations in comb-shaped PPOs (i.e., QC3-PPO and QC6-PPO)), the alkyltrimethylammonium cations of the side-chain PPOs, which do not possess highly reactive benzylic protons adjacent to both the aromatic ring and the cation, showed superior alkaline stability. After 30 days of aging in 1 mol/L NaOH solution at 80 °C, the retention of the conductivities of NC3Q-PPO (IEC = 2.17 mmol/g), NC5Q-PPO-40 (IEC = 2.03 mmol/g), and NC5Q-PPO-60 (IEC = 2.57 mmol/g) were 73.1%, 89.9%, and 81.2% compared with 39.8%, 41.2%, and 56.5% for the QPPO-40 (IEC = 2.27 mmol/g), QC3-PPO-40 (IEC = 2.22 mmol/g), and QC6-PPO-40 (IEC = 2.13 mmol/g) samples, respectively. In addition to good stability, the side-chain NC5Q-PPO-40 and NC5Q-PPO-60 with longer spacers between the aromatic polymer backbone and the cation exhibited high conductivities of 73.9 and 96.1 mS/cm at 80 °C in liquid water, while the swelling ratios were limited to 15% and 28%. The flexible linear spacer in NC5Q-PPO membranes induced distinct hydrophilic/hydrophobic microphase separation, which enhanced the physical properties of the membranes. Thus, we believe that the NC5Q-PPO-type AEMs derive their superior performance from both their unique chemical structures with n-pentyl cationic tethers and the microphase-separated morphologies of the materials driven by the side chain architecture.

Original languageEnglish (US)
Pages (from-to)5321-5330
Number of pages10
JournalChemistry of Materials
Volume29
Issue number12
DOIs
StatePublished - Jun 27 2017

Fingerprint

Polyphenylene oxides
Oxides
Anions
Ion exchange
Negative ions
Membranes
Cations
Positive ions
Aromatic polymers

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

Cite this

@article{35447230d9fa4b07975d57d492e81744,
title = "Cationic Side-Chain Attachment to Poly(Phenylene Oxide) Backbones for Chemically Stable and Conductive Anion Exchange Membranes",
abstract = "A series of chemically stable and ionically conductive side-chain anion exchange membranes (AEMs) based on poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) backbones and alkyltrimethylammonium cations are reported in this work. Two alkyltrimethylammonium groups with n-propyl (C3) and n-pentyl (C5) alkyl chains were tethered onto PPO backbones through secondary amine moieties, resulting in two side-chain AEMs, that is, NC3Q-PPO and NC5Q-PPO and NC5 Q-PPO. In comparison to benzylic QA groups (e.g., benzyltrimethylammonium cations in quarternized PPO (QPPO) and benzylalkyldimethylammonium cations in comb-shaped PPOs (i.e., QC3-PPO and QC6-PPO)), the alkyltrimethylammonium cations of the side-chain PPOs, which do not possess highly reactive benzylic protons adjacent to both the aromatic ring and the cation, showed superior alkaline stability. After 30 days of aging in 1 mol/L NaOH solution at 80 °C, the retention of the conductivities of NC3Q-PPO (IEC = 2.17 mmol/g), NC5Q-PPO-40 (IEC = 2.03 mmol/g), and NC5Q-PPO-60 (IEC = 2.57 mmol/g) were 73.1{\%}, 89.9{\%}, and 81.2{\%} compared with 39.8{\%}, 41.2{\%}, and 56.5{\%} for the QPPO-40 (IEC = 2.27 mmol/g), QC3-PPO-40 (IEC = 2.22 mmol/g), and QC6-PPO-40 (IEC = 2.13 mmol/g) samples, respectively. In addition to good stability, the side-chain NC5Q-PPO-40 and NC5Q-PPO-60 with longer spacers between the aromatic polymer backbone and the cation exhibited high conductivities of 73.9 and 96.1 mS/cm at 80 °C in liquid water, while the swelling ratios were limited to 15{\%} and 28{\%}. The flexible linear spacer in NC5Q-PPO membranes induced distinct hydrophilic/hydrophobic microphase separation, which enhanced the physical properties of the membranes. Thus, we believe that the NC5Q-PPO-type AEMs derive their superior performance from both their unique chemical structures with n-pentyl cationic tethers and the microphase-separated morphologies of the materials driven by the side chain architecture.",
author = "Jing Pan and Juanjuan Han and Liang Zhu and Hickner, {Michael Anthony}",
year = "2017",
month = "6",
day = "27",
doi = "10.1021/acs.chemmater.7b01494",
language = "English (US)",
volume = "29",
pages = "5321--5330",
journal = "Chemistry of Materials",
issn = "0897-4756",
publisher = "American Chemical Society",
number = "12",

}

Cationic Side-Chain Attachment to Poly(Phenylene Oxide) Backbones for Chemically Stable and Conductive Anion Exchange Membranes. / Pan, Jing; Han, Juanjuan; Zhu, Liang; Hickner, Michael Anthony.

In: Chemistry of Materials, Vol. 29, No. 12, 27.06.2017, p. 5321-5330.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Cationic Side-Chain Attachment to Poly(Phenylene Oxide) Backbones for Chemically Stable and Conductive Anion Exchange Membranes

AU - Pan, Jing

AU - Han, Juanjuan

AU - Zhu, Liang

AU - Hickner, Michael Anthony

PY - 2017/6/27

Y1 - 2017/6/27

N2 - A series of chemically stable and ionically conductive side-chain anion exchange membranes (AEMs) based on poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) backbones and alkyltrimethylammonium cations are reported in this work. Two alkyltrimethylammonium groups with n-propyl (C3) and n-pentyl (C5) alkyl chains were tethered onto PPO backbones through secondary amine moieties, resulting in two side-chain AEMs, that is, NC3Q-PPO and NC5Q-PPO and NC5 Q-PPO. In comparison to benzylic QA groups (e.g., benzyltrimethylammonium cations in quarternized PPO (QPPO) and benzylalkyldimethylammonium cations in comb-shaped PPOs (i.e., QC3-PPO and QC6-PPO)), the alkyltrimethylammonium cations of the side-chain PPOs, which do not possess highly reactive benzylic protons adjacent to both the aromatic ring and the cation, showed superior alkaline stability. After 30 days of aging in 1 mol/L NaOH solution at 80 °C, the retention of the conductivities of NC3Q-PPO (IEC = 2.17 mmol/g), NC5Q-PPO-40 (IEC = 2.03 mmol/g), and NC5Q-PPO-60 (IEC = 2.57 mmol/g) were 73.1%, 89.9%, and 81.2% compared with 39.8%, 41.2%, and 56.5% for the QPPO-40 (IEC = 2.27 mmol/g), QC3-PPO-40 (IEC = 2.22 mmol/g), and QC6-PPO-40 (IEC = 2.13 mmol/g) samples, respectively. In addition to good stability, the side-chain NC5Q-PPO-40 and NC5Q-PPO-60 with longer spacers between the aromatic polymer backbone and the cation exhibited high conductivities of 73.9 and 96.1 mS/cm at 80 °C in liquid water, while the swelling ratios were limited to 15% and 28%. The flexible linear spacer in NC5Q-PPO membranes induced distinct hydrophilic/hydrophobic microphase separation, which enhanced the physical properties of the membranes. Thus, we believe that the NC5Q-PPO-type AEMs derive their superior performance from both their unique chemical structures with n-pentyl cationic tethers and the microphase-separated morphologies of the materials driven by the side chain architecture.

AB - A series of chemically stable and ionically conductive side-chain anion exchange membranes (AEMs) based on poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) backbones and alkyltrimethylammonium cations are reported in this work. Two alkyltrimethylammonium groups with n-propyl (C3) and n-pentyl (C5) alkyl chains were tethered onto PPO backbones through secondary amine moieties, resulting in two side-chain AEMs, that is, NC3Q-PPO and NC5Q-PPO and NC5 Q-PPO. In comparison to benzylic QA groups (e.g., benzyltrimethylammonium cations in quarternized PPO (QPPO) and benzylalkyldimethylammonium cations in comb-shaped PPOs (i.e., QC3-PPO and QC6-PPO)), the alkyltrimethylammonium cations of the side-chain PPOs, which do not possess highly reactive benzylic protons adjacent to both the aromatic ring and the cation, showed superior alkaline stability. After 30 days of aging in 1 mol/L NaOH solution at 80 °C, the retention of the conductivities of NC3Q-PPO (IEC = 2.17 mmol/g), NC5Q-PPO-40 (IEC = 2.03 mmol/g), and NC5Q-PPO-60 (IEC = 2.57 mmol/g) were 73.1%, 89.9%, and 81.2% compared with 39.8%, 41.2%, and 56.5% for the QPPO-40 (IEC = 2.27 mmol/g), QC3-PPO-40 (IEC = 2.22 mmol/g), and QC6-PPO-40 (IEC = 2.13 mmol/g) samples, respectively. In addition to good stability, the side-chain NC5Q-PPO-40 and NC5Q-PPO-60 with longer spacers between the aromatic polymer backbone and the cation exhibited high conductivities of 73.9 and 96.1 mS/cm at 80 °C in liquid water, while the swelling ratios were limited to 15% and 28%. The flexible linear spacer in NC5Q-PPO membranes induced distinct hydrophilic/hydrophobic microphase separation, which enhanced the physical properties of the membranes. Thus, we believe that the NC5Q-PPO-type AEMs derive their superior performance from both their unique chemical structures with n-pentyl cationic tethers and the microphase-separated morphologies of the materials driven by the side chain architecture.

UR - http://www.scopus.com/inward/record.url?scp=85021398299&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85021398299&partnerID=8YFLogxK

U2 - 10.1021/acs.chemmater.7b01494

DO - 10.1021/acs.chemmater.7b01494

M3 - Article

VL - 29

SP - 5321

EP - 5330

JO - Chemistry of Materials

JF - Chemistry of Materials

SN - 0897-4756

IS - 12

ER -